Strength Training Helps Prevent and Fight Cancer
There is plenty of evidence that that people with high levels of muscular strength have a lower risk of cancer – a 40% lower risk to be exact. A study looked at almost 9,000 men aged 20-82 and found that men with a stronger one-rep max on bench press and leg press had a 40% reduction in their risk of dying from cancer. They adjusted for body mass index (BMI), body fat, and aerobic fitness and the results still held.
There seems to be something about simply being stronger that is associated with a lower our risk of getting cancer. In addition, strength actually seems to lower our risk of dying from most major health issues. For instance, men with a lower vertical leap, less sit-ups, and decreased grip strength have a higher risk of dying period.
Studies seem to suggest that strength is independently associated with a lower risk of cancer and a higher chance of avoiding an early death, regardless of age, smoking, alcohol usage, or other health issues. Now this is all well and good but associations can only tell us so much so we have to understand the mechanisms that support these associations.
How do Muscles Fight Cancer and other diseases?
We know that exercising our muscles leads to:
- Improved insulin sensitivity (lowers insulin because less insulin needed to remove sugar from our blood)
- Increased sugar uptake by skeletal muscle and used for energy during exercise
- Less cancer promoting sugar and insulin floating around our blood
- A decrease in the levels of hormones that can lead to cancer. For instance, resistance training increases IGFBP-3, which binds to insulin-like growth factor (IGF), decreasing its ability to promote cancer (growth factors are normal within the human body, but too many can lead to excessive cellular growth, including cancer growth)7
- Decreased inflammation (which when present, accelerates cancer)
- Increased antioxidant defense, which helps fight potential cancer-causing free-radicals
- Lowers inflammation producing body fat
In addition, we are learning that our body fat works like an endocrine organ – secreting inflammatory hormones and an excess of potentially cancer-stimulating hormones. Estrogen, which is a hormone that both men and women require to function normally is a great example. When too much is secreted from higher than optimal body fat levels, Estrogen can increase a woman’s risk of breast cancer. When women lower body fat levels, estrogen levels decrease.
Fat is not the only recently discovered endocrine organ. Muscle functions in this way but to our benefit! Muscles secretes IL-6 which tempers excessive inflammation. IL-6 is a myokine. A Myokine is an endocrine hormone produced by muscle and released during contraction.
While Body Fat secretes the pro-inflammatory cytokine TNF-α ( tumor necrosis factor), our muscles secrete IL-6, which fights inflammation. As bad as fat is generally considered, muscle seems to stand in direct opposition to fat physiologically, and TNF versus IL-6 further embodies this difference.
- Fat-derived TNF is inflammatory, while muscle-derived IL-6 is anti-inflammatory.
- Muscle-derived IL-6 signals to our body to break down lipids and burn fat.
- TNF causes insulin resistance and impairs glucose uptake by our cells (both leading to increased blood sugar).
- While serious and often fatal events like septic shock cause a sudden release of TNF, excess body fat causes the ongoing chronic release of harmful TNF.
- Muscle-derived IL-6 helps regulate AMPK (while muscle contraction directly activates AMPK), which stimulates the breakdown of fat and cholesterol, stimulates our mitochondria (energy factories of the cells), and potentially fights cancer.
AMPK, or AMP-activated protein kinase, is an enzyme produced extensively in our muscles, liver, and brain. It serves as an energy sensor and regulator and closely monitors changes in energy status based on our dietary and activity levels. AMPK works to supply more ATP (energy). Simply put AMPK signals our cells that it is not a time for building, but rather for breaking down.
The Benefits of Resistance Training
While muscles secrete IL-6 all the time, exercise increases this release up to 100 times. Those of us that exercise and contract our muscles frequently experience a sensitization to IL-6 when not exercising and at rest. The more we contract our muscles the more we accentuate the benefits of IL–6. The amount of IL-6 produced depends on several factors including:
- Intensity of the exercise
- Duration of the exercise
- Endurance capacity
- Size of muscle contracting
Muscles can help fight cancer – so everyone should be doing resistance training to build more muscle and increase strength! Muscles can help prevent cancer but you have to use them to generate all the positive adaptive responses that prevent and mitigate cancer and other diseases!